The invention relates to a method for the generative production of a component and a device for carrying out such a method.
In a generative production process such as SLM (Selective Laser Melting), defects in the component may arise due to different causes. The defects may lead to a reduction in the quality of the component and are conventionally found only by testing the finished component. Examples of defects are microcracks, foreign inclusions, and undigested material. The tests are either destructive or non-destructive. Destructive tests, however, require the production of a large number of components or test specimens. Non-destructive test methods such as, e.g., x-ray computed tomography, are technically complex, time-consuming and costly. Actually, by monitoring the temperature and the geometry of the melting bath, conclusions relative to the component can be drawn indirectly, but this testing technique does not make possible a more precise control of the material properties and the recognition of defects.
A method for non-destructive process control during generative production is described in the publication EP 1 815 936 B1. In this method, an ultrasound testing is conducted during the production. Optionally, an eddy-current testing may accompany the ultrasound testing. A disadvantage in this method, however, is that a plurality of material layers are detected or scanned by the sound field and/or the eddy field and thus individual material layers cannot be accurately detected. Ultrasound testing also requires a complex system control. Actually, eddy-current testing can basically be operated with a penetration depth such that individual material layers can be detected exclusively. But test frequencies are necessary to do this that require, for example, a calibration of the eddy-current sensors that cannot be justified with reasonable expenditure, as well as lift-off effects.